78 L. Agassiz on the Ichthyological Fauna of Western America. 
larger teeth, increasing gradually in size and thickness from the 
upper margin of these bones towards their symphysis. The differ- 
ence in form of these bones arises from the circumstance that the 
slight ridge upon the outer surface of the arch in Carpiodes is 
plane, meeting under an acute angle. This structural homology 
is satisfactorily traced by the difference in the external appear- 
ance of these two planes, the posterior one being full as the pos- 
terior half of at outer surface of the arch in Carpiodes, 
whilst the anterior plane is coarsely porous, indeed studded with 
deep. pits analogous to the porous character of the anterior half 
of the onter surface of that bone in Carpiodes. The teeth them- 
selves are compressed; their grinding edge is rather blunt, slightly 
arched in the middle, and provided with a little cusp along the 
inner margin which is hardly detached from the crown.and does not 
se above its surface, as in eH Ichthyobus and Cycleptus. 
boKigs 2, a, represents the right 
ryugeal seen from behind, a/ boiipehe 
crest of teeth, a’ the armature of the 
anterior edge of the inner curve, 6 one 
of the lower, ¢ one of the middle, and 
d one of the upper teeth. 
In this genus the bulk of the body is 
not placed so far forwards as in Carpio- 
des, thé greatest height being midway 
between the head and, tail. The up- 
per outline of the body i is less strongly 
arched in advance of the dorsal ; the 
head is longer than high, and the 
snout not more prominent than the 
mot The mouth opens ig 
dowuwards aud forwards, the low 
jaw being nearly as long as the up 
The lips are small and Gemininteds 
The anterior rays of the dorsal are not separately F peoloileed 
beyond the rest of the fin, though its anterior margin is higher 
than its middle and posterior portion. The lower fins are as in 
arpiodes. 
A 
Zs 
Ay 
okt 
DD) PN 
yy 
‘The scales have many narrow radiating furrows upon the an- 
terior field, none across the lateral fields, and few upon the pos- 
terior field, converging to the centre of radiation to which the 
tubes of the lateral line extends also. For this new eae I pro- 
pose the name of Bubal sia eg to recall the name of 
Buffalo fish, commonly appl its species. To this genus 
belong the species I have ascribed as C us Urus from the 
‘Tennessee River,* C. Taurus from Mobile River, and C. Vitulus 
* See this Journal, 2nd Ser, vol, xvii, p. 355 and 356. 
